The major vascular systems of the developing fetus are formed by vasculogenesis, a developmental process in which mesoderm is transformed in situ into endothelial cells. The goal of my work is to discover how mesoderm is transformed into the endothelial cell lineage using the mouse allantois as a model in vitro system.
During its early development, the murine allantois consists of an inner core of mesoderm and an outer layer of squamous epithelium referred to as a mesothelium. The allantois undergoes two major developmental processes:
(i) maturation and fusion with the chorion to become the umbilical component of the chorioallantoic placenta, and
(ii) vascularization, forming an artery and a vein that permit within the chorionic disk the exchange of nutrients, metabolic wastes and gases with the mother during fetal gestation (K. M. Downs and R. L. Gardner, Development 121:407-416, 1995; K. M. Downs and C. Harmann, Development 124:2769-2780, 1997; K. M. Downs, et al., The Murine Allantois. In Current Topics in Developmental Biology (eds. R. Pedersen and G. Schatten). New York: Academic Press. 39:1-33, 1998; K. M. Downs, supra, 1998).
In one embodiment, the present invention is a method for evaluating the effect of test compounds, preferably potentially harmful or beneficial substances, on formation of blood vessels during vasculogenesis. In one embodiment, this method comprises direct application of a test compound to cultured allantoic explants. In another embodiment, one would evaluate test compounds by DNA uptake and expression of a test compound by the mesenchymal cells of allantoic explants.
In another embodiment, the present invention is the delivery of factors into the umbilical circulation by formation of chimeric allantoises. Preferably, this delivery ameliorates or eliminates developmental defects through delivery of therapeutic factors.
In another embodiment, the present invention is the delivery of factors into the umbilical circulation by formation of chimeric allantoises. Preferably, this delivery ameliorates or eliminates developmental defects through delivery of therapeutic factors found in normal allantoic cells.
In another embodiment, the present invention is the delivery of gene expression products into the umbilical circulation by formation of a chimeric allantois. This method comprises the step of transfection of mesenchymal cells with heterologous genes expressed from appropriate endothelial cell promoters and introducing the donor mesenchymal cells into a developing allantois. Once integrated into the vasculature, the cells will express the gene product and deliver it to the bloodstream of the fetus. Preferably, the gene product is a therapeutic protein targeted to a fetus with particular developmental defects.
In another embodiment, the present invention is a method of fetal gene therapy comprising the step of creating a chimeric allantois/umbilical cord. Specifically, the method involves identifying a fetus with a genetic defect and obtaining compatible allantois/umbilical cells capable of expressing a gene product that would ameliorate this defect. The cells are introduced into the exocelomic cavity of the defective embryo or transplanted into the conceptus and assimilated into the native allantois/umbilical cord. Thus, a chimeric allantois/umbilical cord is produced. The gene product is then delivered into the fetus via the umbilical blood vessels. Preferably, the fetus is a mammalian fetus. Most preferably, the fetus is a human fetus.
In another embodiment, the present invention is a method of delivering a heterologous protein to a fetus via obtaining compatible allantois/umbilical cells capable of expressing a gene product and introducing these cells into the exocelomic cavity of an embryo or transplanting the cells onto the embryo and assimilating them into the native allantois/umbilical cord. A chimeric allantois/umbilical cord is produced and the gene product is then delivered into the fetus via the umbilical blood vessels.
In another embodiment, the present invention is a method of fetal gene therapy comprising the step of creating a chimeric allantois/umbilical cord by obtaining allantois cells compatible with a fetus with a genetic defect that express a gene product that ameliorates the genetic defect. The cells are then transplanted into the fetus wherein the transplanted cells develop into endothelial cells which line the vasculature of the umbilical cord and release the gene product into the bloodstream of the fetus.
The present invention is also a population of transgenic allantois cells, wherein the transgene may be a therapeutic gene and/or a marker or reporter gene.
It is an object of the present invention to provide a method of human fetal gene therapy.
It is another object of the present invention to provide a method of human fetal gene therapy that would benefit continued therapy after birth because the supplemented gene product would be recognized as xe2x80x9cselfxe2x80x9d by the adult immune system.
Other advantages, objects and features of the present invention will be obvious after review of the specification, drawings and claims.